Mounting and protecting electrical apparatus



Jan. 16, 1923.

D. F. WHITING. MOUNTING AND PRoTEcTING ELECTRICAL APPARATUS FILED JUNE 1 1920.

WOQQQQQF Patented Jan. 16,1923.

UNITED STATES PATENT OFFICE.

DONALD F. WHITING, F NEW YORK, N. Y., ASSIGNOR TO WESTERN ELECTRIC COMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

MOUNTING `AND IROTECTING ELECTRICAL APPARATUS.

Alipiication mea :une i, 1920. serial No. 385,439.

To all whom 'it may concern.'

Be it known that I, DONALD F. WHITING, a citizen of the United States, residing at New York lin the county of Bronx, State of New York, have invented certain new and useful Improvements in Mounting and Protecting Electrical Apparatus, of which the-following is a full, clear, concise, and

. exact description.

This invention relates to electrical systems and has particular reference to the mounting of telephone lrepeater equipment on anel boards or racks.

ne object of the invention is to most effi ciently `reduce the cross-talk which may occur between adjacent pieces of apparatus.

Another object is to substantiallyy eliminate the possibility that such apparatus as vacuum tubes, used in repeaters, shall become overheated due to inefiicient dissipation of the heat generated by them during their operation.

The invention in generalcomprises, in the first place, the interposition between pieces of apparatus between which cross-talk is likely to occur, of other pieces of apparatus used on the panels, which have metallic casings which are grounded and act as magnetic shields. On such racks it has been found that the input and output transformers, the variousbatteries and potentiometers can thus be used. Since these pieces of apparatus are already in use on racks of this type, the practice of the invention does not re uire any1 additional apparatus.

urthermore, it has been found that the vacuum tubes become overheated when their space relations with respect to the other aparatus on the racks are not proper. yThis invention therefore further involves the assembly of the apparatus on the racks so that open spaces as large as possible shall be provided around the vacuum tubes and that.

the general disposition of the tubeson the racks shall be such as will forni vertical flues or channels up which the air heated by the tubes may pass Without obstruction.

Furthermore, the invention involves the assembly, close together, of those pieces of apparatus of higher impedance so that they shall have little or no effect on the other parts- Further objects of the invention will be made apparent in the following detailed description taken in connection with the ac- .companying drawing. in which Fig. 1 is a noted in heavy black lines.

As shown in Fig. l, the panel board coinprises a plurality of vertical bars 5, to which are suitablyfastened tiers of racks 6. Each rack is provided with a complete set of repeater apparatus which may' be used in two o r four wire circuits. In view of the necessity of using large numbers of these racks,

'they must be placed as close together as possible in the interest of economical spacing, and therefore it has been found that unless special provision isY made, cross-talk will occur between apparatus on one rack and that on others either vertically or horizontally adjacent thereto. In referring to a piece of apparatus on the racks in Fig. 1 by number, the corresponding part of the circuit in Fig. 2 will be denoted with the i same number so that the circuit relation of the apparatus shown on a rack in Fig. 1 may be readil ascertained from Fig. 2.

Consi ering the middle rack shown in Fig. 1, and noting the apparatus on thisV rack from left to right, there is a potentiometer 7, a relay 8, aninput transformer 9 and condensers 10, 11 and 11.

order are a vacuum tube 12, a resistance potentiometer 13 "and its mounting plate 13, and another vacuum tube 14, to the right of which are batteries 15 and 16.

` It will be noted that in Fig. 3, the connecting wires between input transformer 9 and the grid of the vacuum tube 1,2, the connecting wires between the plate of` vacuum tube 12 and the potentiometer 13, and the connecting wire between the potentiometer 13 and the grid of vacuum tube 14, are shown in heavy black lines. This is to indicate that these wires and the parts to which they are connected are of high impedance with respect to ground. If, these wires are placed closely adjacent to portions of other circuits to which cross-talk might be transmitted, such an action is likely to take place. Therefore, it becomes necessary that Next in tiometer 7 on the rack above or below, there are disposed the metallic casings ot condensers 10, 11 and 11 and transformer '9, all

- of which casings are grounded. rlhis arrangement of apparatuslhas been found bymany and exhaustive tests to substantially eliminate cross-tall: between the above mentioned two pieces of apparatus. 1t has also been found Ithat cross-talk may occur between tube 12 on one rack and 14 on another. ln order that this detect may be eliminated, it will be noted that on any two adjacent racks between the tube 12 and the tube 14, there is schematically represented the groundedend of the potentiometer 13 which in this instance acts eftectualiy as a shield.

Furthermore, it has been found that crosstalk occurs between tube 14C and potentiometer l von adjacent racks. Accordingly, this defect is eliminated by the interposition of thecasings of batteries 15 and 16 bctween the tube 1st and potentiometer 7. These casings being grounded, they form an effectual shield between the parts mentioned. Furthermore, it will be noted that the transformer 9, vacuum tubes 12 and 1d, and the upper end of the potentiometer 13, which are of hi h impedance, are located 'adjacent to portions of the rack immedi- -ately above them on which grounded -apparatus is located and which therefore is ot' zero potential. v

lt will furthermore be noted that the various vacuum tubes on the racks are arranged in such a vertical relation thati'airly open' spaces are provided around each tube and corresponding tubes of'4 each rack are arranged in vertical series so that the heat generated by the tubes tends to pass upwardly alongthis channel or flue. The-formation of these lues is further aided by the depth dimensions ofthe transformers 9, the potentiometer 13, and the battery boxes v.15 as clearly shown by the cross-section in Fig. 2. llt has been 'found that the tendency to overheat on the part oi the vacuum tubes is therefore very efficiently reduced.

A circuit-arrangement of the same general type as the one shown in Fig. 2 is described in my Patent No. 1,378,392, May 17, 1921,

signaling systems.

What is claimed is:

1. Amplifying means, said vmeans lcomprising a vertical row of amplifying tubes and circuit apparatus auxiliary thereto, said Maaate circuit apparatus being so arranged later-A board, the majority of said 'apparatus projecting from said board adistance substantially at leastas far as sald tubes, said apparatus being so arranged with respect to said tubes that vertical lues are provided for the air heated during the operation of said tubes.` l

3. A telephonerepeater panel board comprising a plurality of repeater racks, apparatus oneach rack of high impedance with respect to ground, and a plurality of grounded magnetic shields between this ap.- paratus o n adjacent racks.

d. Atelephone repeater panel board Comprising a plurality of repeater racks, apparatus on each rack adapted to a'ect apparatus on other racks to produce crosstalk, and a grounded shield between said apparatus on adjacent racks.

5. A telephone repeater panel board comprising a plurality of repeater racks, ap.

paratus on each rack of high impedance to ground, said racks lbeing so disposed that said high impedance apparatus is adjacent a piece of apparatus of substantially zero potential to ground on an adjacent rack.

6. A telephone repeater panel board comprising a plurality of repeater racks, apparatus of high impedance to ground on each rack,V said apparatus being substantially surrounded by grounded apparatus to prevent cross-talk between racks.

7. A telephone repeater panel board comprising a plurality of repeater racks, devices mounted on each of said racks, said devices on each rack comprising a thermionic discharge tube, ya potentiometer and condensers having grounded metallic casings, certain of said condensers being so interposed between a device on one rack and a potentiometer on an 'adjacent rack as to prevent,i cross-talk therebetween.

8.- A 'telephone repeater panel board com prising a plurality of repeater racks, devices; mounted on each of said racks, said devices. on each rack comprising a thermionic dieA charge tube, a potentiometer and batteri-e1 having grounded metallic casings, certai`r oi said' batteries being so interposed betwee,4 a device on one rack and a potentiometer o= an adjacent rack as to prevent cross-tall-y therebetween. p,

9. `A telephone repeater panel board comprising a plurality of repeater racks, devices mounted on each of said racks, said devices on each rack compr1s1ng a transformer having a grounded metalllc casing, an electron les and circuit apparatus auxiliary theretol mounted on each of saidv racks, certain of said devices on one rack tending to affect certain of said devices on another rack to produce crosstalk, and a grounded shield-` ingnieans between said certain devices on said one rack and said certain devices on said other rack.

11. A panel board comprising racks, rdevices comprising thermionic discharge tubes and circuit. apparatus auxiliary thereto mounted on each of said racks, certain of said devices on each rack being of high 20 impedance to ground, said devices and racks being so disposed that said certain devices on one rack are adjacent devices of substantially zero potential to ground on an adjacent rack. v

e 12. A panel board comprising racks, devices mounted on each of said racks, said deviceson `each rack comprising thermionic discharge tubes and circuit apparatus auxiliary thereto, certain of saiddevces on 30 each rack being grounded, and others of said devices on each rack having high impedance to ground and being substantially surrounded by said grounded devices.

' -In witness whereof, I doV hereunto sub- 35 scribe my name this 27 day of May A. D.,

DONALD F. WHITING. 

